04goat350

iTrader: (1)

For a 04 GTO m6 looking to make around 450 at the wheel give or take which 5.3 heads would be better the 63cc heads or the 67cc for the combustion chamber?

jdaniels

iTrader: (12)

You'll make more N/A power with the 63cc chambers due to higher compression. Depending on your budget, I would go with a 243 (ls6) casting. If you really want truck heads, I have a set of stockers that I put LS6 springs on that you can have for $150. I'll deliver them to you...

Canbarelygo

in reality the 5.3s i would think would be the much cheaper better option. if your talkin after market they flow very very close in aftermarket form to the ls6 head in aftermarket form with a smaller combustion chamber. i think there n/a it would be a no brainer to go with the 5.3s. if we are talkin budget id still say go 5.3s i got my 5.3 heads valve jobbed and surfaced and had my ls1 valves stuck in em and when it was all said and done i had just 300 bucks in them including buying them

jdaniels

iTrader: (12)

In aftermarket form, a ***** out to the limits ported 5.3 head flows about the same as a barely ported LS6 head. A max effort port on an LS6 head is superior in every way. Chamber size is irrelevant at that point as you can choose your combustion chamber size for either when you order them.

01ssreda4

iTrader: (96)

A 243/799 head is a better head IMO. It can be milled for compression if that's desired but not always needed. A well put together combo does not need to run on the ragged edge to produce results, meaning PTV clearance, compression, shift rpms etc.